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Wave Injection at Low Latitudes
Mark Golkowski
Remediation of Enhanced Radiation Belts Workshop
Lake Arrowhead, CA
March 3-6, 2007
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Adelaide, Australia
~500 kW ? Navigation transmitter in Komsomolsk na Amur in Russian far east (400 msec pulses) at L = 2
Conjugate point in southern Australia
Stanford University receiver since January 2007
Explore and quantify wave-growth
Stanford Scientists Kangaroos
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Russian Alpha Transmitters
3.6 second pattern (six 0.6s segments) 400ms pulses, 200ms off between pulses Three sites alternate among 3 frequencies
14.88 kHz
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Historical Background
Triggered emissions have been observed from other mid-latitude transmitters: NAA (L=2) 14.5 kHz, 200 msec pulses
Whistler-mode Komsomolsk Alpha pulses have been studied by Tanaka et al. 1987 in the context of whistler propagation characteristics
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Example 1-Hop
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2
1A
Becc
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Temporal (non-linear) Growth
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Example Growth
~7-8 dB total
~70-80 dB/sec
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Example Growth
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Example Detection
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10-Day Statistics (1-10 April)
Count of 1-hop observations in synoptic (1min/5min) recordings
10 days during and after a geomagnetic disturbance
1-Hop observations show qualitative relationship to geomagnetic activity
Need more data to quantify relationship
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Diurnal patterns
Day DayNight Day DayNight
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Average Daily Variations
Sunrise
Sunset
Tanaka et al. 1987 Stanford 2008
Diurnal variation shows maxima after sunset and sunrise
Tanaka et al. 1987: diurnal variation is same for whistlers and is a propagation effect (duct formation, coupling in/out of duct)
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Summary
1-Hop echoes regularly observed from Komsomolsk Alpha transmitter
Echoes exhibit temporal growth of ~70-80 dB/sec Propagation delays of 460 msec – 540msec
equatorial electron concentrations of 4000-5000 cm-3 at L = 2
Triggered of frequency emmisions not observed yet, except perhaps on DEMETER satellite
Diurnal variations likely result from propagation/ducting effects
Future Work: statistically quantify effect of geomagnetic conditions on wave growth